The classification of the various groups of society, or the division of human society into classes, is as logical a process, that is, a result attained by the operations of reason, as the division of animals, plants, and minerals into various classes. A specific group of social beings, which bear the stamp of common characteristics, is put in a certain class by social science. This classification cannot be made by purely empirical methods of immediate sensuous perceptions. It cannot be determined from the appearance of modern men, whether they are capitalists or workers. We must look for certain scientifically established features which determine the social classification of men. As we have just seen, Marx held economic facts to be fundamental, and he contended that the economic characteristics were valid for purposes of classification. In his view, the manner in which a specific human group obtained its sustenance was the chief characteristic. Men whose chief means of life are wages form the working class. Men whose most important source of livelihood is the ownership of capital (land, buildings, workshops, and raw material) form the capitalist class. It is of little moment that a worker owns a savings-bankbook, and draws interest or dividends from a co-operative society, or that a capitalist personally supervises his undertaking, or organises his business, so that his profits partly consist in wages of superintendence or salary. The outstanding feature is that the chief interest of the worker is concentrated on wages, whilst that of the capitalist is directed on property. It goes without saying that the social classes are not completely homogeneous. Like botanical and zoological classes, they may be divided into kinds and species; the working classes include well-paid hand and brain workers, as well as sweated sections; but all the subdivisions of the social classes possess the common outstanding quality of the same source of livelihood, which is either personal labour or the possession of capital. One class disposes only of labour-power, while the other class owns the means of production.